Method and apparatus for building a real time graphic scene database having increased resolution and improved rendering speed

ABSTRACT

A database generated off-line containing high-resolution models incorporated into source imagery. The method and apparatus builds a data intensive scene representation and renders it off-line, captures an orthographic projection of the rendered scene and stores it as a pixel representation of the rendered imagery and models. The pixel representation is stored in a database for rendering in real time. The resulting database can be rendered more efficiently in real time than databases built using previously known techniques. The database provides improved resolution and improved rendering performance. Resolution is enhanced by generating and placing images of higher-resolution models onto lower-resolution models. Performance is enhanced by reducing the number of polygons that must be rendered in real time to represent a scene. The method and apparatus provides an orthographic rendering of a scene wherein images of high-resolution models (SPLOT models) have been inserted into lower-resolution source imagery. The resulting rendered representation of a scene is stored in a database for rendering in real time.

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, but otherwise reserves all copyright rightswhatsoever.

FIELD OF THE INVENTION

The present invention relates generally to the field of computergraphics and specifically to the field of creating a database withimproved performance and resolution for large areas rendered in realtime. The present invention presents a method and apparatus for creatinga database that enhances the resolution of a scene and renders moreefficiently in real time.

BACKGROUND OF THE INVENTION

Typical graphics rendering systems utilize a geotypical texturedatabase, wherein geotypical textures are stored in memory and utilizedto fill in textures for every occurrence of a particular texture, forexample a cornfield. The geotypical cornfield texture is held in memoryand used repeatedly on every polygon that represents a small section ofthe cornfield. Typically, there are many corn field texture polygonsrequiring the geotypical cornfield texture to be used thousands of timesin a scene containing cornfields. Thus, such a geotypical database woulduse a large number of polygons to represent the surface of the earth.

Real time rendering requires that each polygon undergo a mathematicaltransformation, a matrix multiplication within each display frame to mapeach polygon from world coordinates to display coordinates. Typicalgraphics rendering systems have limited processing power to render alarge number of polygons in real time, thus the presence of the polygonsslows down system performance during real time rendering. Thus, there isa need for a method and apparatus that reduces the number of polygonsthat must be processed in real time rendering.

Current rendering systems can display large geospecific images, however,resolution of those graphics rendering systems is limited to theresolution of the source imagery. Thus, there is a need for a method andapparatus that enables enhancement of rendered imagery beyond theresolution of the source imagery.

There is also a shortage of high-resolution imagery data coverageworldwide. In many cases only low-resolution imagery is available and insome cases no imagery is available. Thus, there is a need for a methodand apparatus that enables the creation of real time scenery in areaswhere there is no source imagery available.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for building adatabase off-line that can be used to efficiently render a scene in realtime. The present invention enables creation of a database comprised ofhigh-resolution models incorporated into lower-resolution sourceimagery. The present invention renders and captures an orthographicprojection of a scene and stores it as a pixel representation of therendered imagery and the models. The pixel representation is stored in adatabase for rendering in real time. The resulting database can berendered more efficiently in real time than databases built usingpreviously known techniques.

The database provides improved resolution and improved renderingperformance. Scene resolution is enhanced by substituting images ofhigh-resolution geotypical textures and models in place oflower-resolution source imagery. The present invention builds a databasegenerated from an orthographic rendering of a enhanced scene whereinimages of high-resolution models (SPLOT models) have been inserted intolower-resolution source imagery. The rendered representation of thescene is stored in a database for rendering in real time.

The present invention builds a database containing high-resolution pixelrepresentations and lower-resolution polygonal representations, therebyenabling switching between the pixel representation for two-dimensionalrendering and the polygonal representation of a feature for threedimensional rendering in a scene. The present invention generates adatabase that enables efficient rendering in real time.

The present invention removes excess polygons from culture to speed upthe real time rendering process. A visual database generally includespolygons that represent the undulating surface of the terrain, plusadditional polygons that represent cultural features on the terrain. Thepresent invention reduces the polygons that represent cultural featuresby replacing them with textures derived from said polygons. For example,a database may contain polygons with a geotypical cornfield texture,said polygons coplanar with the polygons representing the terrainsurface; and other polygons with a geotypical runway texture, saidpolygons also coplanar with the terrain surface; and other polygons thatrepresent paint markings on said runway, coplanar with the runwaypolygons; and polygons used to represent three-dimensional features (forexample, buildings) on the terrain. All such cultural polygons may bereplaced by a single large texture applied to the terrain surfacepolygons, said texture derived from the polygons representing thecornfields, the runways with its surface markings, and the buildings.Said texture may be considered as pseudo-geospecific. inasmuch as itappears very similar to high-resolution imagery, were such imageryavailable.

The present invention provides a method and apparatus that enablesconstruction of a database having fewer polygons to enable higherperformance rendering in real time. The present invention also enablescreation of synthetic high-resolution imagery where no source imagery isavailable. The present invention also provides an apparatus and methodfor enhancing the resolution of a representation of source imagery.

The present invention renders a polygonal representation of a scene(geometry and texture) containing high-resolution models, as anorthographic projection and then captures a pixel representation of anorthographic projection of the scene. The orthographic pixel texturesare combined into a composite texture. The resulting composite textureis then draped over the surface contour. The composite texture can berendered rapidly because the bulk of the cultural features have beentransformed from a polygonal representation to a texture representation.The initial underlying polygons, representing the culture which slowdown real time rendering, are no longer a part of the scene. The presentinvention also removes two-dimensional coplanar polygons. Thus, thepresent invention enables rendering a scene with a fraction of thepolygons utilized in typical graphical rendering systems. The presentinvention provides essentially the same scene content with an order ofmagnitude reduction in the number of polygons, an increase in resolutionand additional coverage in areas where source imagery is unavailable.

Resolution is effectively increased in selected target areas. Forexample, in a five-meter resolution source image, the present inventionenables an operator to mark, locate and digitize features such as roadsbuildings and fields that appear in the image. For example, a road in afive-meter resolution image may be visible but not as sharp as desired.The present invention provides a method and apparatus for sharpening thepresentation of the road in the image. The present invention provides amethod and apparatus for creating models comprised of polygons andhigh-resolution textures to replace or create the features in an image,thereby increasing the overall imagery resolution.

The present invention enables replacement of original features withsharper, higher-resolution models. The same process can be used tocreate and add features such as parking lots, buildings and fields thatmay or may not appear in the source imagery. The resulting intermediateimage comprises a combination of the five-meter resolution sourceimagery and the higher-resolution models. The combination yields animage with higher resolution than the original five-meter sourceimagery.

The present invention renders an orthographic projection of the sceneincluding the models at higher resolution than the source imagery. Forexample, a one-meter resolution orthographic projection rendering isperformed for a five-meter resolution source imagery scene containingsub-meter resolution model textures. Thus, the one-meter orthographicprojection effectively under samples the sub-meter resolution modeltexture and over samples the five-meter texture surrounding the model.Thus, the orthographic projection provides higher resolution in thetarget area comprising the models and is sharper than the original imagein the target area. Moreover, the higher-resolution imagery correlateswell with the original imagery so that the enhanced image looks like thescene in the original image. The resulting synthetic imagery alsocorrelates well with the high-resolution polygon scene.

The present invention enables an operator to select features in thesource imagery for digitization and replacement with high-resolutionmodels or he may chose to add high-resolution models for features thatdo not appear in the source imagery. The orthographic rendering ispreferably performed by Vega, which is available from ParadigmSimulation, Inc., Dallas, Tex. and runs on the Onyx2 computer systemshown in FIG. 1. There are a plurality of commercially availablegraphics rendering tools and hardware platforms that can be used togenerate an orthographic projection of a scene.

Feature addition is useful when source imagery is lacking. Five-metersatellite imagery is scarce and when available may be classified.Moreover, there are gaps in coverage where no imagery is available.Satellite imagery also presents cloud coverage problems when cloudsobscure portions of the imagery. Additionally, satellite imagery isoften taken at different times of year so adjacent shots do not matchand do not create a coherent mosaic, for example, summer in one sectionand snow covered in winter in another section so adjacent sections donot match. Thus, satellite imagery, even if available, is problematic.The present invention enables scene generation without any sourceimagery. The present invention enables generation of a scene from mapsof surface contours and features without actual source imagery.

Correlation of source imagery can be problematic. Often database imageryis created from different sources. Oftentimes feature location data andsource imagery does not correlate well. The present invention creates adatabase that generates imagery that does correlate well because itgenerates enhanced-resolution features by referencing source imagerypixels.

The present invention enables an operator or an artificially intelligentfeature recognition process to recognize and digitize features fromvarious sources, including topographical maps. The present inventionenables input of features from such sources. For example, topographicmaps may illustrate trails, which divide small areas into differenttypes of fields. The present invention enables an operator to usecommercially available tools to digitize these fields and arbitrarilyassign geotypical textures to each field. The present invention enablesan operator to locate and draw or digitize features such as primary,secondary and tertiary roads. High-resolution models are substituted forselected features so that primary roads are replaced with a geotypicalmodel of a superhighway, secondary roads are replaced with a two lanehighway model, and tertiary roads are replaced with a dirt road model.

The present invention enables creation of a geospecific database basedon feature location data from a map of features, without using sourceimagery. Such a database enables generation of a real time database,which for example, can be used in a flight simulator to train a pilot tofly over and become familiar with a geographic area for which sourceimagery is not available. The present invention enables creation ofimagery scene data that correlates well with actual source imagery. Thesynthesized scene database can be created without source imagery andlooks realistic. A pilot trained on such a database would recognize theactual physical terrain, even though the database was created withoutsource imagery.

Orthographic projection is well known graphic rendering technique forgraphic rendering tools such as Vega. The present invention creates acomposite texture database by systematically stepping over theorthographic projection of a scene and capturing a pixel representation,section by section. The present invention captures a pixelrepresentation of each section of the orthographic image and places themaltogether in one large composite texture pixel representation. Thecomposite texture is mapped onto the polygonal terrain contour for thescene and placed in the database for real time rendering.

A preferred embodiment utilizes a Silicon Graphics, Inc.Performer-compatible clip map data structure for storing the levels ofdetail used in rendering an image in real time. The clip map containsall the resolution sets for an image. For example, for atwenty-five-meter resolution source image, the clip map would containthe twenty-five-meter resolution image, and reduced-resolution data setsat fifty meters, one hundred meters, two hundred meters and so on, atprogressively lower resolutions. The present invention propagates thesynthetic imagery throughout the lower levels of detail stored in theimage clip map.

The present invention, for example, builds a one-meter resolution imagein the clip map from high-resolution geotypical textures and then downsamples that image to create lower-resolution images at two meters, fourmeters, eight meters, etc. The present invention continues generation ofreduced-resolution data sets until it has generated and placed thegeotypical texture in every resolution level of the clip map. Thepresent invention replaces source imagery with enhanced-resolutionimagery that includes higher-resolution models for features of interest.The enhanced feature model is propagated into every level of the clipmap for the scene.

Thus, an original twenty-five-meter source imagery resolution data setcontains a one-meter model of a road rather than the original road thatwas captured at twenty-five-meter resolution. Thus, the road now appearssharper than it did in the original source imagery. As an observerutilizing the database moves closer in on a displayed scene andapproaches the enhanced feature, it appears at higher and higherresolution, and there is a smooth transition through all the resolutiondata sets presented in the clip map. For example, the one-hundred-meterimagery blends into the fifty-meter imagery, which blends into thetwenty-five-meter imagery, because all resolution sets are derived fromthe highest-resolution image data.

The present invention enables replacement of a single feature or anentire scene with a high-resolution model embedded in source imagery.The present invention utilizes Multigen 11 to build geometric modelsthat are then embedded into source imagery to sharpen, replace or createfeatures for inclusion in a real time database. The present inventionremoves any polygons that are coplanar or insignificant to simplify andreduce the number of polygons used to represent the geometric model.

For example, to build a scene of the tabletop with a sheet of paper,cups, and an ice bucket, the present invention generates a pixelrepresentation of the tabletop with all the objects on it. Individualpolygons typically carry the image texture for the tabletop and each ofthe objects on the tabletop. The present invention renders the typicaltextures polygons for the objects laying on the table to create a pixelrepresentation or picture of the tabletop texture with everything on it.The repeating geotypical table texture is replaced with a largergeospecific texture for the entire tabletop.

Viewing the table top scene at a distance, there is no three-dimensionalperspective of the objects on the table top, thus the present inventiondoes not render the objects on the table top with all the polygonsrequired for three-dimensional presentation of the objects. The presentinvention renders a two-dimensional pixel representation of the tabletopthat includes the objects on the tabletop. When the observer perspectivecloses in on a feature, the present invention switches from thetwo-dimensional pixel representation to a polygonal three-dimensionalrepresentation of the feature so that the rendered feature manifeststhree-dimensional relief.

Switching from a two-dimensional pixel representation of an object to athree-dimensional polygonal representation also helps to prevent loss oftexture sharpness that occurs at close range when the relative size ofthe texels representing a feature become larger than a screen pixel. Inorder to retain sharpness in the image the present invention switches tothe three-dimensional polygonal representation of the feature comprisinga geotypical textured model polygonal representation of the feature. Theresulting database enables creation of an image that renders efficientlyin real time and correlates well with original source objects.

Prior to the present invention, the typical graphics rendering apparatusor method encountered performance bottlenecks due to excessive polygonusage in texture representations. Thus, to reduce the number of polygonsneeded to render an image in real time, the prior graphic renderingmethod and apparatus had to settle for coarser representations offeatures using less polygons or fewer features. Typically, prior methodsforced a reduction in geometric complexity to achieve rendering speed.The reduction in polygons also reduced resolution and informationcontent in a polygonal representation of an image. For example, apolygonal representation of a curved road using fewer polygons had lessresolution and would make the road appear choppy when compared to apolygonal representation of the same road rendered using more polygons.This trade off between performance and image complexity has beendiminished by the present invention. The present invention insteadimproves both performance and image complexity while increasing theresolution of a scene rendered using fewer polygons than the previoustypical known methods.

In one aspect of the present invention a method is presented forbuilding a database for real time rendering of a scene comprising thesteps of substituting a high-resolution polygonal feature model for afeature in scene source imagery: systematically rendering said scenecontaining said high-resolution model:

capturing a pixel representation of said rendered scene containing saidhigh-resolution model; and

storing said pixel representation of said rendered scene containing saidhigh-resolution model in a database for real time rendering of saidscene. In another aspect of the present invention a method is presentedfurther comprising the step of systematically rendering an orthographicprojection of said scene containing high resolution models. In anotheraspect of the present invention a method is presented for building adatabase for real time rendering of a scene comprising a polygonalrepresentation having coplanar polygons and feature identification codesfor polygons comprising the steps of substituting a high-resolutionpolygonal feature model for a feature in scene source imagery;systematically rendering said scene containing said high-resolutionmodel; capturing a pixel representation of said rendered scenecontaining said high-resolution model; and storing said pixelrepresentation of said rendered scene containing said high-resolutionmodel in a database for real time rendering of said scene. In anotheraspect of the invention a method is presented further comprising thesteps of removing polygons having a particular feature code from saidpolygonal representation of scene to create a reduced polygonrepresentation; and storing said reduced polygonal representation ofsaid scene in a data base for rendering in real time. In another aspectof the present invention a method is presented comprising the steps of:removing coplanar polygons from said polygonal representation of sceneto create a reduced polygon representation; and storing said reducedpolygonal representation of said scene in a data base for rendering inreal time. In yet another aspect of the present invention a method ispresented further comprising systematically rendering an orthographicprojection of said scene containing high resolution models; removingcoplanar polygons from said polygonal representation of scene to createa reduced polygon representation; removing polygons having a particularfeature code from said polygonal representation of scene to create areduced polygon representation and storing said reduced polygonalrepresentation of said scene in a data base for rendering in real time.

In another aspect of the present invention an apparatus is presented forbuilding a database for real time rendering of a scene comprising meansfor substituting a high-resolution polygonal feature model for a featurein scene source imagery; means for systematically rendering said scenecontaining said high-resolution model; means for capturing a pixelrepresentation of said rendered scene containing said high-resolutionmodel: and means for storing said pixel representation of said renderedscene containing said high-resolution model in a database for real timerendering of said scene. In yet another aspect of the present inventionan apparatus is presented further comprising means for systematicallyrendering an orthographic projection of said scene containing highresolution models. In another aspect of the present invention anapparatus is presented for building a database for real time renderingof a scene comprising a polygonal representation having coplanarpolygons and feature identification codes for polygons comprising: meansfor substituting a high-resolution polygonal feature model for a featurein scene source imagery; means for systematically rendering said scenecontaining said high-resolution model; means for capturing a pixelrepresentation of said rendered scene containing said high-resolutionmodel; and means for storing said pixel representation of said renderedscene containing said high-resolution model in a database for real timerendering of said scene. In another aspect of the present an apparatusis presented further comprising means for removing polygons having aparticular feature code from said polygonal representation of scene tocreate a reduced polygon representation, and means for storing saidreduced polygonal representation of said scene in a data base forrendering in real time. In another aspect of the present an apparatus ispresented further comprising means for removing coplanar polygons fromsaid polygonal representation of scene to create a reduced polygonrepresentation; and means for storing said reduced polygonalrepresentation of said scene in a data base for rendering in real time.In another aspect of the present an apparatus is presented furthercomprising means for systematically rendering an orthographic projectionof said scene containing high resolution models.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the Onyx2 computer system comprising ahardware environment for a preferred embodiment of the presentinvention;

FIG. 2 is data flow diagram for a process comprising a preferredembodiment of the present invention.

FIGS. 3A and 3B are data flow diagram for an overview of a set ofprocesses comprising a preferred embodiment of the present invention.

FIG. 4 is data flow diagram for the Feature, Geometry and TextureModeling process comprised in a preferred embodiment of the presentinvention.

FIG. 5 is data flow diagram for the Build Contour process comprised in apreferred embodiment of the present invention.

FIG. 6 is data flow diagram for the Project Culture process comprised ina preferred embodiment of the present invention.

FIG. 7 is data flow diagram for the Build Structure process comprised ina preferred embodiment of the present invention.

FIG. 8 is data flow diagram for the Make Color SPLOT Texture processcomprised in a preferred embodiment of the present invention.

FIG. 9 is a data flow diagram for the Make Radiance SPLOT Textureprocess comprised in a preferred embodiment of the present invention.

FIG. 10 is a data flow diagram for the Build Lower Levels of Detailprocess comprised in a preferred embodiment of the present invention.

FIG. 11 is a data flow diagram for the Ortho Camera process comprised ina preferred embodiment of the present invention.

FIGS. 12-17 comprise a source code listing for process Make SPLOTTexture which captures orthographic images of terrain creating ageospecific imagery of a synthetic environment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The following is a detailed description of a preferred embodiment of themethod and apparatus of the present invention. Turning now to FIG. 1, apreferred embodiment of the hardware rendering means for the presentinvention is illustrated. The present invention renders imagery off lineand in real time utilizing commercially available Performer running onthe Onyx2 Infinite Reality (hereinafter Onyx2) computer system, both ofwhich are manufactured and distributed by Silicon Graphics. Inc.,Mountain View, Calif.

The Onyx2 computer system comprises basic building blocks comprising, asshown in FIG. 1, processor 18, secondary cache 14, processor 16,secondary cache 15, main memory 19, directory memory 12, addresscontroller 13 and Hub ASIC 17 that connects the processors, main memoryand its associated directory memory, through a dedicated router port,and the Input/Output subsystem. The native graphics programminginterface for Onyx2 is OpenGL. OpenGL is designed to be independent ofoperating systems and window systems, and is supported on virtually allworkstations and personal computers available in the industry today. TheSilicon Graphics Onyx2 hardware and associated software are described inthe Onyx2 Technical Report, October 1996, published by Silicon Graphicsand hereby incorporated by reference.

Turning now to FIG. 2, a process comprising a preferred embodiment ofthe present invention is presented. In a preferred embodiment of thepresent invention the means for Building a Geometric Computer Model 25comprises Multigen If, a software apparatus available from Multigen,Inc., San Jose, Calif. Multigen If comprises software that executes inconjunction with a processor, memory, and inputs means as shown in FIG.1. In a preferred embodiment, process Build Geometric Computer Modelinputs Geometric Models 26 (three-dimensional polygonal representationsof houses, trees, etc.), Geotypical Textures 21 (which are mapped ontothe models), Digital Elevation Data 22 (representing contour of theterrain), Vector Feature 23 data (representing locations and types offeatures) and Source Imagery 24 data.

In a preferred embodiment, source imagery is processed so that selectedcultural features are digitized to become vector feature datarepresentations. The present invention replaces the vector feature datawith high-resolution three-dimensional polygonal models containinggeotypical textures. These polygonal models and textures are embeddedwithin the source imagery that is imported along with the associatedDigital Terrain Elevation Data 22 to the process Build GeometricComputer Model 25.

Process Build Geometric Computer Model 25 generates and outputs HighLevel of Detail Geometric Model (“Terrain Database”) 28 data and SPLOTModels 29 data. High Level of Detail Geometric Model data 28 is passedto process Build Lower Levels of Detail 31. Process Build Lower Levelsof Detail 31 simplifies High Level of Detail Geometric Model 28 byremoving coplanar and insignificant polygons and outputs SimplifiedGeometric Model 33 data.

In a preferred embodiment the means for Building Lower Levels of Detail31 and means for Simplifying the Geometric Model 33 comprise thehardware and software apparatus shown in FIG. 1 implementing the stepscomprising process Build Lower Levels of Detail 31. Process BuildBackground Image Texture 27 inputs Imagery 24 data products, joins themtogether forming a mosaic, and reformats the imagery for rendering.Process Build Background Image Texture 27 generates and outputs ImageBased Texture 30 data.

The High Level of Detail Geometric Model 28 data, SPLOT Models 29 dataand Image Based Texture 30 are input to the process SystematicallyRender Computer Model 32 that renders a computer model comprised ofSPLOT Models 29 data, High Level of Detail Geometric Models 28 data andImage-Based Texture 30 data. Process Systematically Render the ComputerModel 32 renders a computer model utilizing an orthographic projectioninto a matrix of synthetic texture and imagery tiles.

In a preferred embodiment, means for Systematically Rendering theComputer Model using an orthographic projection into a matrix ofsynthetic texture/imagery tiles 32 comprises process Make Color SPLOTTexture 47, Make Radiance SPLOT Texture 71, and process Ortho Camera 39,implemented on an Onyx2 computer system, as shown in FIG. 1. Thus thepresent invention utilizes imagery and geometric models and producesSynthetic Texture 34 data. Process Render Scene 35 receives inputsSimplified Geometric Model 33 data. High Level of Detail Geometric Model28 data and Synthetic Texture 34 data. In a preferred embodiment, themeans for performing Render Scene 35 comprises the commerciallyavailable Vega, manufactured and distributed by Paradigm Simulation,Inc., Dallas, Tex.

Vega comprises a software environment that runs on top of Performer onthe Onyx2 computer system shown in FIG. 1. There are a number of toolsavailable to render a scene using the database comprising SimplifiedGeometric Model 33 data, High Level of Detail Geometric Model 28 dataand Synthetic Texture 34 data as generated by the present invention. Thepresent invention provides a method and apparatus for building asimplified geometric model that resembles a two-dimensional version ofthe highest level of detail of the integrated source models, elevation,features and imagery.

Turning now to FIGS. 3A and 3B, the process shown in FIG. 2 is brokendown into more specific processes providing a detailed specific exampleof the present invention. The components of the process shown in FIG. 2map onto FIG. 3 processes. Process component Build Geometric ComputerModel 25, which builds a high level of detail model, is broken down intofour processes as shown in FIG. 3. Process Feature Geometry and TextureModeling 40 receives inputs source DFAD (digital feature analysis data)48, Source Maps 49 data and five-meter Color Imagery 56 data. DFADcomprises digital vector data, wherein features are described in termsof lines, points and polygons, for example, a line representing a road.The Feature Geometry and Texture Modeling process 40 uses the SourceDFAD 48 data and Source Maps 49 data to generate Models and Textures 50data, FLOP commands 51, processed DFAD 52 and SPLOT Models and Textures53 data. The FLOP commands 52, Models and Textures 50 and processed DFADare output by process Feature Geometry and Texture Modeling 40.

Process Project Culture 42 inputs the FLOP commands 51 vector data(which describes the locations of features, including roads, lakes,buildings, etc.) and converts the vector data into three-dimensionalgeometry, a process well known in the art. The processed DFAD 52 data isused by the Project Culture 42 process, implemented in a preferredembodiment by the Multigen 11 tool. Models and Textures 50 data are theinstances of features that are projected. For example, a FLOP commanddescribes models and locations of models, which enables the ProjectCulture 42 process to add models to the database at specified locations.

Process Build Contour 41 inputs source Digital Terrain Elevation Data(DTED) 47 and builds Base Contour Geometry 54. Base Contour Geometry 54,in a complex database is divided into a plurality of sections and levelsof detail regarding the terrain surface. The Feature Geometry andTexture Modeling process outputs are added to the highest level ofdetail for the image.

Process Build Lower Levels of Detail 31 removes coplanar andinsignificant polygons from the highest level of detail to produce lowerlevels of detail. Thus, process Build Lower Levels of Detail 31 mapsonto Build Geometric Computer Model 25 and Build lower Levels of Detail31 of the process shown in FIG. 2. A preferred means for comprisesprocess Building Lower Levels of Detail implemented on the Onyx2computer system shown in FIG. 1. Process Build Lower Level of Detail isillustrated in FIG. 11.

Process Build Structure 43 is another process comprised in BuildGeometric Computer Model 25. The Build Structure 43 process divides ascene geometry or contour database into a grid. Sections of the gridform aggregations referred to as contour tiles and contour regions.These aggregations make the contour data easier to manage by a renderingsystem. Contour tiles represent a plurality of geometry polygon files inthe database. Contour regions reference a plurality of contour tiles.For example, there may be approximately three hundred contour regionsreferenced that represent and bind together approximately ten thousandunderlying polygon files in a database.

Vega utilizes the contour regions to render a scene. Process BuildStructure 43 generates Compiled Geometry 62 or contour regions that havebeen reformatted for rapid loading and rendering by process Render withVega 35. Process Build Structure 43 also generates a Vega ApplicationDefinition File (ADF) 65 that contains information to direct processRender with Vega 35 regarding which database portions to load forrendering.

Process Render with Vega 35 inputs Vega Regions 66 and Vega Clip Objects67 and 68. The clip objects associate database portions or files in thedatabase with a particular image. The ADF file defines the regions andclip objects. Vega associates files in the database with an image. Theclip objects indicate which files use particular source imagery or SPLOTimagery. Thus Vega utilizes the Vega regions and Vega Clip objects torender an image in real-time.

Process Build Background Image Texture 27 comprises process Build ColorImagery Texture 45 and Build Radiance Imagery Texture 46. Process BuildColor Imagery Texture 45, for example, may receive high- andlow-resolution imagery inputs of five-meter Color Imagery 56 andforty-meter Color Imagery 57. Process Build Color Imagery Texture 45integrates the five-meter Color Imagery 56 data and forty-meter ColorImagery 57 data, builds a Clip stack and outputs Color Image Texture 60data. The Color Image Texture 60 data comprises an aggregation offive-meter Color Imagery 56 and forty-meter Color Imagery 57. ColorImage Texture 60 data output comprises a composite image made up offive-meter and forty-meter imagery data.

In a preferred embodiment of the present invention, five-meter andthirty-meter image data are provided from satellite imagery. Satelliteimagery transforms the physical earth into film or an electronicrepresentation. The present invention transforms the film or electronicrepresentation of the physical earth into a real time database andrenders the representation in real time. In a preferred embodiment ofthe present invention the thirty-meter data is used to fill in gaps thatmay occur in the five-meter imagery data coverage, since thirty-meterresolution imagery data is available in a much broader geographic areathan five-meter imagery data.

In a preferred embodiment of the present invention, process Build ColorImagery Texture 45 builds a clip stack. A clip stack is amulti-resolution data structure comprising the resolution sets necessaryfor rendering an image. The clip stack is a data structure compatiblewith the Onyx2 computer system shown in FIG. 1. The clip stack containsa copy of imagery data at low resolution, and a copy at successivelyhigher resolutions. In a preferred embodiment, high-resolution andlow-resolution imagery, for example, the present invention buildsnineteen resolution levels for an image, for example, input sourceimagery may be input at five-meter and forty-meter resolution. In apreferred embodiment, for example, the forty-meter imagery data isstored in resolution level five and the five-meter imagery data isstored in resolution level two. The present invention producesresolution level one, which is higher resolution than the originalsource imagery data.

A similar processing path is utilized to create resolution sets forreflectance or radiance data. Build Reflectance Imagery Texture 46inputs five-meter Reflectance Imagery 58 data and thirty-meterReflectance Imagery 59 data to produce Reflectance Image Texture 61 datacomprising the resolution sets for Reflectance or infrared data.

Process Systematically render the computer model using an orthographicprojection into a matrix of synthetic texture and imagery tiles, whichis labeled in FIG. 3 as Make SPLOT Texture 32 comprises processes OrthoCamera 39, Make Color SPLOT Texture 47 and process Make Radiance SPLOTTexture 71. Process Make Color SPLOT Texture 47 inputs Color ImageTexture 60 data, Compiled Geometry 62 data (contour region files) andSPLOT Models and Textures 53 (alternate feature representations, forexample, shadows in place of trees, higher-resolution detailed models inplace of simple models used in real time rendering).

Process Make SPLOT Texture 32 inputs SPLOT Models and Textures, combinesthese models and textures as alternative representations of featureswith source imagery data and passes all inputs to Process Ortho Camera39 for rendering as an image. Process Make SPLOT Texture 32 processesthe rendered image, generates and outputs the Color SPLOT texture 63data. The Color SPLOT Texture 63 data is in the same format as ColorImage Texture data, but additionally includes higher-resolution SPLOTmodels. The Color SPLOT Texture 63 data is a pixel representation orimage of an orthographic projection or rendering of the polygonal scenewhich may include source imagery, feature polygons, and high-resolutionSPLOT models. FIGS. 12-17 comprise a source code listing for processMake SPLOT Texture 32 which captures orthographic images of terraincreating a geospecific imagery of a synthetic environment.

Process Render with Vega 35 inputs Vega Clip Objects 67 from Color SPLOTTexture 63 and Vega Clip Object 68 data from Radiance SPLOT Texture 64and Vega Regions 66 from Compiled Geometry 62 data. Process Render withVega 35 utilizes these inputs to render the scene that has now beenprocessed to add in the higher-resolution SPLOT texture. The presentinvention substitutes simplified polygonal models are for real timerendering.

Turning now to FIG. 4, process Feature, Geometry and Texture Modeling 40takes in source DFAD 48 and Extracts Feature Codes 80 and builds aFeature Code Database 81. DFAD comprises linear features (for example,roads), arial features (for example, lakes), and point features (forexample, buildings). The Feature Code Database is a list of featurecodes and descriptive information regarding the feature data. Theprocess determines the contents of the data, for example, whether or notit contains roads, trees, buildings, etc. Data content is determined byextracting and examining the feature codes. The source DFAD 48 is alsoimported to Arc/Info 82 and placed into the Feature Database 83. Culturecan be removed based on feature code.

The present invention enables five-meter Imagery 84 Registration andDigitization 86. The present invention also enables Maps 85 Registrationand Digitization 87. Vector feature data from the Feature Database 83 isdisplayed on a display screen along with satellite imagery forcomparison and alignment. Road vectors, for example are aligned tocorrelate or align with the actual roads they represent in sourceimagery. Also, as provided by the present invention, features that arevisible in the five-meter Imagery 84 or Maps 85 but are not present inDFAD are added by drawing in and digitizing features, creating vectordata out of imagery and map data by drawing features digitally. Addingfeatures enables enhanced population of the feature database.

Process Align Features/Edit/Fix 89 edits, corrects and registers theFeature Database 83 with source imagery, after which, vector datarepresenting features better correlates with the feature locations inthe imagery. DFAD is exported 102 to Processed DFAD 91 and FLOP Commandsare exported 103 to Flop Commands 90. Process Texture Modeling 92 inputsPhotographs 93 or pictures of models and edits them to generate TypicalTextures 94. Typical Textures 94 are output to Process Geometry Modeling95. In a preferred embodiment, a polygon editor Multigen If is providedto generate geometric Models 96 comprising polygons and textures.

Model dimensions 97 are extracted and placed in Model Statistics 98.Model Statistics 98 are used to Integrate and Update 99 the Feature CodeDatabase 81 that is used to align features properly. For example, if ahouse model is located next to a road, the house model may be too big,so that the house model would overlap the road. Thus, a discrepancyreport 105 for model improvement is created and sent to process GeometryModeling to correct the misalignment by using a smaller house model thatdoes not overlap the road. This process ensures that features do notoverlap on the final scene database.

Turning now to FIG. 5, Process Build Contour 41 inputs DTED Cells 110(cells comprise one degree of latitude and one degree of longitude, anapproximately sixty miles square surface area on the earth's surface)that are reformatted to Make DED files 111 for compatibility withMultigen 11 and stored in one degree Digital Elevation Models 112. TheDED files use Make Ded Big File 113 to merge all DED files into DatabaseWide Digital Elevation Model 114. DTED artifacts, which occur whenjoining adjacent DTED cells, are filtered out 115 and placed in theDatabase Wide Digital Elevation Model 116. Commercial Tools such asMultigen 11 are means provided by the present invention to BuildGeometry (sample elevation data and build geometry polygons) and ApplySurface Normals 117 (taking the angle information out of the elevationdata using the angle attribute of the geometry).

Map Clip Texture 119 associates or maps texture onto contour for everyvertex in the terrain, with or without data present in the terrain ortexture image. Every polygon vertex in the terrain receives a texturecoordinate. Process Apply Feature Codes 120 places feature codes on theterrain resulting in the Base Contour Geometry (highest Level of Detail)118. Base Contour Geometry 118 comprises a contour made from digitalelevation data with geospecific textures mapped onto it, even though thetextures may not yet exist, their geographic coverage is known.

Turning now to FIG. 6, now that the contour is built, process ProjectCulture 42 inputs the highest level of detail of the contour. BaseContour Geometry (highest level of detail) 130 and scales the BaseContour Geometry 130 to provide a higher-resolution solution for DFADprojection. Process Project Culture then projects Processed DFAD 52 datausing Multigen 11 onto the scaled highest level of detail contour. BaseContour Geometry 132. The data is then unscaled to form the highestlevel of detail with Projected Culture 134. Flop Commands 51 are used toproject additional culture 135 to generate Base Contour Geometry 134(highest level of detail) as the contour highest level of detail withadditional culture. Process Reap Clip Texture 136 applies photo imagetexture to the additional photo culture by remapping the clip texture sothat it receives texture coordinates relative to the geospecific imagerather than typical textures.

Process Check and Fix attributes 137 performs quality control functionson the data, corrects texture paths, corrects data artifacts, andensures that all polygons have a feature identification code. The endproduct is the highest level of detail contour with additional projectedculture. Process Build lower Levels of Detail 31, shown in FIG. 3creates lower levels 141 of detail by stripping off the two-dimensionalculture polygons and texture polygons from the contour highest level ofdetail, Base Contour Geometry 134.

Turning now to FIG. 7, process Build Structure 43 inputs Base ContourGeometry (highest level of Detail) 140 localizes 142 the data so thatthe coordinates for each tile are local to the center of the tile,instead of all tile coordinates being relative to one common origin andstores the localized data in Localized Contour Geometry 144 (highestlevel of detail). Process Build Structure 43 inputs Base ContourGeometry (Lower Levels of Detail) 141 localizes 143 Base ContourGeometry 141 and stores the localized data in Localized Contour Geometry(Lower Levels of Detail) 145.

Process Build Structure 43 inputs Clod definition of Contour 147 data,which is the definition of the organization of all the contour regions,tiles, and geometry files, builds 148 contour tiles 151, builds 149Contour Regions 152 and builds 150 Vega Application Definition Files153. Process Compile PFB 146 optimizes the regions for processing andoutputs Compiled Geometry 154. Vega accepts the Compiled Geometry 154product for rendering. Vega Application Definition File (ADF) 153 is thedefinition of regions as part of the database used in rendering theimage in real time. The Application Definition File (ADF) informs Vegaas to which regions to use when rendering. As shown in FIG. 3. ProcessRender with Vega 35 uses the Vega ADF 65 and Vega regions 66, which arethe contour regions PFB or Compiled Geometry 154. The ADF specifies Vegaregions data.

Vega Clip Objects 67 and 68 define large textures generated by processMake SPLOT Texture 47 and Make Radiance SPLOT Texture 32, respectively.Previously the large texture has been mapped onto the geometry, however,mapping occurred before the texture was defined. Thus, in rendering,Vega uses the previous mapping to combine the texture (Vega clipobjects) with the geometry of the scene. Because the imagery andgeometry are joined together late in the processing path, the presentinvention enables selection of which image to place on the geometry asspecified in the ADF file. Thus, the ADF may specify mapping a colorimage, infrared image or no image onto the geometry.

Turning now to FIGS. 10 and 11, process Make Color SPLOT Texture 47 andprocess Make Radiance SPLOT Texture 71 illustrate the present inventiongenerating composite textures and higher-resolution imagery. As shown inFIG. 8, process Make Color SPLOT Texture 47 inputs Compiled Geometry 62comprising Contour Region PFB or imagery contour, Color Image Texture 60Resolutions two through nineteen (comprising formatted source imagery)and SPLOT Models and Textures 52 comprising high-resolution polygonalfeature models and textures into process Ortho Camera with Vega 162. Thepresent invention renders an orthographic projection comprising theColor Imagery Texture 161, SPLOT Models and Textures 52 and CompiledGeometry 62 together into a pixel representation comprising Color SPLOTTexture Resolution One (highest resolution) 163.

Process Integrate SPLOT into background imagery 164, inputs Color SPLOTTexture Resolution One 163 and Color Image Texture Resolutions 2 through19 and integrates them to generate Color SPLOT Texture (all resolutions)165, a texture image of the rendered scene for resolution levels onethrough nineteen, The source code for Make Color SPLOT Texture isincluded in the software appendix.

Turning now to FIG. 9, a similar process is performed by process MakeReflectance SPLOT Texture 71. As shown in FIG. 9, process MakeReflectance SPLOT Texture inputs Compiled Geometry 62 comprising ContourRegion PFB or imagery contour, Reflectance Image Texture 61 resolutionstwo through nineteen comprising formatted source radiance imagery andSPLOT Models and Textures 52 comprising high-resolution polygonalfeature models and textures into process Ortho Camera with Vega 168. Thepresent invention renders an orthographic projection comprising theReflectance Imagery Texture 61, SPLOT Models and Textures 52 andCompiled Geometry 62 together into a pixel representation comprisingReflectance SPLOT Texture Resolution One (highest resolution) 169. Thepresent invention utilizes geometry and imagery resolution levels twothough nineteen and produces a higher-resolution image, resolution levelone.

Process Integrate SPLOT into background imagery 170, inputs ReflectanceSPLOT Texture olution one 169 and Reflectance Image Texture Resolutionstwo through nineteen and integrates them generate Reflectance SPLOTTexture (all resolutions) 171, a texture image containing SPLO modelsresolution levels one through nineteen.

Turning now to FIG. 10, process Build Lower Levels of Detail 31comprises Remove Polygons Matching A List Of Feature Codes 36, RemoveCoplanar Polygons 37 and Replace SPLOT models with Runtime Models 38. Ina preferred embodiment, all features and culture have a featureidentification code. Process Remove Polygons Matching a List of FeatureCodes 36 removes polygons based on feature dentification code. Forexample, all instances of a corn field feature, for example, can beremoved.

Process Remove Coplanar Polygons 37 removes redundant contour polygons.The present invention preferably builds a database such that polygonscan be identified as coplanar and can later be removed. Coplanarpolygons or sub-face polygons, which are subordinate to another face orpolygon, do not contribute to the contour and thus are removed from themodel after rendering and imaging the model. The present inventionpreferably builds a scene as sub-face polygons, renders and images itusing Ortho Camera and removes the sub-face polygons to create a reducedpolygon representation. The source code process Remove Coplanar Polygons37, Remove Polygons Matching a List of Feature Codes 36 is included inthe software appendix.

Process Replace SPLOT Models with Runtime Models places a simplifiedreduced polygonal model to replace the high polygon usage detailed SPLOTmode utilized to render an orthographic projection. An alternative meansfor Building Lower Levels of Detail 31 comprises the process implementedon a Multigen 11, available from Multigen, Inc., San Jose, Calif.

Turning now to figure 11, process Ortho Camera process Render ScaledScene 172 uses Vega to render a scene scaled to a specified resolutionper pixel. A scene can be scaled so that a 512×512 meter area ofcoverage is displayed within a 512×512 pixels area, thereby generatingresolution of one meter per pixel. Ortho Camera renders and captures512×512 pixels at a time. Process Acquire 512×512 Pixels 173 acquiresand stores the 512×512 pixel scaled image. Process Move to Adjacent512×512 then moves to an adjacent 512×512 pixel area. This acquisitionprocess is repeated until it acquires the entire scene, resulting inImage at Resolution Specified 175 data that is used by Process MakeColor SPLOT Texture 47 and Make Radiance SPLOT Texture 71. The sourcecode for process Ortho Camera is included in the software appendix.

The foregoing example is but one of many implementations of the presentinvention. The present invention is not limited by the foregoingexample, but instead limited by the following claims and theirequivalents.

What is claimed is:
 1. A method for building a database for real timerendering of a scene comprising (a) substituting a high-resolutionpolygonal feature model generated from vector feature data as a featureinto three-dimensional scene source imagery in place of a lowerresolution polygonal representation of the feature; (b) systematicallyrendering a two-dimensional representation of the three-dimensionalscene source imagery of step (a) containing the high-resolution model,(c) capturing a two-dimensional pixel representation of said renderedscene of step (b)containing said high-resolution model; (d) removing theinserted high resolution model from the scene source imagery andsubstituting the lower resolution polygonal representation of thefeature into the source imagery; and (e) storing said two-dimensionalpixel representation of said rendered scene containing saidhigh-resolution model in a database for real time rendering of saidscene, wherein the two-dimensional representation of the scene isrendered on a display viewed from a first observer perspective and thethree-dimensional representation of the scene is rendered on the displaycontaining the lower resolution polygonal feature when the scene isviewed from a second observer perspective closer than the first observerperspective.
 2. The method of claim 1 wherein step (b) comprisessystematically rendering lower resolution data sets of an orthographicprojection of said scene containing high resolution models.
 3. A methodfor building a database for real time rendering of a scene comprising apolygonal representation having coplanar polygons and featureidentification codes for polygons comprising: (a) substituting at leastone high-resolution polygonal feature model generated from vectorfeature data as a feature into three-dimensional scene source imagery inplace of a lower resolution polygonal the feature; (b) systematicallyrendering a two-dimensional representation of the three-dimensionalscene source imagery of step (a) containing the high-resolution model;(c) capturing a two-dimensional pixel representation of the renderedscene of step (b) containing said high-resolution model; (d) removingthe high resolution feature model inserted into the scene source imageryand substituting the lower resolution polygonal feature into the sourceimagery; and (e) and storing said two-dimensional pixel representationof said rendered scene containing said high-resolution feature model ina database for real time rendering of said scene wherein thetwo-dimensional representation of the scene is rendered on a displayviewed from a first observer perspective; and the three-dimensionalrepresentation of the scene source imagery containing the lowerresolution polygonal feature is rendered on the display when the sceneis viewed from a second observer perspective closer than the firstobserver perspective.
 4. The method of claim 3 further comprising thesteps for: (e) removing all inserted feature model polygons having aparticular feature code from said polygonal representation of scene tocreate a reduced polygon representation; and (f) storing as lowerresolution data sets said reduced polygonal representation of said scenein a data base for rendering in real time.
 5. The method of claim 3further comprising the steps for: (e) removing inserted polygons fromsaid polygonal representation of scene to create a reduced polygonrepresentation; and (f) storing said reduced polygonal representation ofsaid scene in a data base for rendering in real time.
 6. The method ofclaim 3 wherein step (b) comprises systematically rendering anorthographic projection of said scene containing high resolution models.7. The method of claim 6 further comprising the step of: (e) removinginserted polygons from said polygonal representation of scene to createa reduced polygon representation.
 8. The method of claim 7 furthercomprising the step for: (f) storing said reduced polygonalrepresentation of said scene in a data base for rendering in real time.9. The method of claim 6 further comprising the step for: (e) removinginserted polygons having a particular feature code from said polygonalrepresentation of scene to create a reduced polygon representation. 10.The method of claim 8 further comprising the step for: (f) storing saidlower polygonal representation of said scene in a data base forrendering in real time.
 11. A apparatus for building a database for realtime rendering of a scene comprising: (a) means for substituting ahigh-resolution polygonal feature model generated from vector data as afeature into three-dimensional scene source imagery in place of a lowerresolution polygonal representation of the feature; (b) means forsystematically rendering a two-dimensional representation of thethree-dimensional scene source imagery of step (a) containing thehigh-resolution model; (c) means for capturing a two-dimensional pixelrepresentation of the rendered scene of step (b) containing thehigh-resolution model; (d) means for removing the high resolution modelinserted into the scene source imagery; (e) means for storing thetwo-dimensional pixel representation of said rendered scene containingsaid high-resolution model in a database for real time rendering of saidscene; (f) means for rendering the two-dimensional representation of thescene on a display viewed from a first observer perspective; and (f)means for rendering the three-dimensional representation of the scene onthe display containing the lower resolution polygonal feature when thescene is viewed from a second observer perspective closer than the firstobserver perspective.
 12. The apparatus of claim 11 wherein means (b)further comprises means for systematically rendering an orthographicprojection of lower resolution data sets of said scene containing highresolution models.
 13. An apparatus for building a database for realtime rendering of a scene comprising a polygonal representation havingcoplanar polygons and feature identification codes for polygonscomprising: (a) means for substituting a high-resolution polygonalfeature model generated from vector data as a feature into scene sourceimagery in place of a lower resolution polygonal representation of thefeature; (b) means for systematically rendering a two-dimensionalrepresentation of the three-dimensional scene source imagery of step (a)containing said high-resolution model; (c) means for capturing atwo-dimensional pixel representation of the rendered scene containingsaid high-resolution model; (d) means for removing the inserted featuremodel inserted into the scene and substituting the lower resolutionpolygonal representation of the feature into the source imagery; and (e)means for storing said two-dimensional pixel representation of saidrendered scene containing said high-resolution model in a database forreal time rendering of said scene; (f) means for rendering thetwo-dimensional representation of the scene on a display at a firstobserver perspective; and (g) means for rendering the three-dimensionalrepresentation of the scene on the display containing the lowerresolution polygonal feature when the scene is viewed from a secondobserver perspective closer than the first observer perspective.
 14. Theapparatus of claim 13 further comprising: means for removing insertedpolygons having a particular feature code from said polygonalrepresentation of scene to create a reduced polygon representation; andmeans for storing said reduced polygonal representation of said scene ina data base for rendering in real time.
 15. The apparatus of claim 13further comprising: means for removing coplanar polygons from saidpolygonal representation of scene to create a reduced polygonrepresentation; and means for storing reduced resolution data sets ofsaid reduced polygonal representation of said scene in a data base forrendering in real time.
 16. The apparatus of claim 13 wherein means (b)further comprises means for systematically rendering an orthographicprojection of the scene containing high resolution models.
 17. Theapparatus of claim 16 further comprising: means for removing insertedpolygons from said polygonal representation of scene to create a reducedpolygon representation.
 18. The apparatus of claim 17 furthercomprising: means for storing said reduced polygonal representation ofsaid scene in a data base for rendering in real time.
 19. The apparatusof claim 16 further comprising: means for removing inserted polygonshaving a particular feature code from said polygonal representation ofscene to create a reduced polygon representation.
 20. The apparatus ofclaim 18 further comprising: means for storing said reduced polygonalrepresentation of said scene in a data base for rendering in real time.21. A system of interconnected programmed computer processors forbuilding a database for real time rendering of a scene comprising: (a) afirst computer processor with storage and including processes forsubstituting a high-resolution polygonal feature model generated fromvector data as a feature into three-dimensional scene source imagery inplace of a lower resolution polygonal representation of the feature,processes for systematically rendering a two-dimensional scene of thescene source imagery containing said high-resolution model, processesfor capturing a two-dimensional pixel representation of said renderedscene containing said high-resolution model, processes for removing thehigh resolution models inserted into the scene source imagery andsubstituting the lower resolution polygonal representation of thefeature into the scene source imagery; and (b) a second computerprocessor with storage and including processes for storing saidtwo-dimensional pixel representation of said rendered scene containingsaid high-resolution model in a database for real time rendering of saidscene; and (c) a third computer processor with storage and includingprocesses for rendering the two-dimensional representation of the sceneon a display viewed from a first perspective and rendering thethree-dimensional representation of the scene on the display containingthe lower resolution polygonal feature when the scene is viewed from asecond observer perspective closer than the first observer perspective.22. The system of claim 21 wherein the first processor further comprisesprocesses for systematically rendering an orthographic projection ofreduced resolution data sets of said scene containing high resolutionmodels.
 23. A computer processor for building a database for real timerendering of a scene comprising a polygonal representation havingcoplanar polygons and feature identification codes for polygonscomprising: (a) a programmed computer processor with storage andincluding processes for inserting a high-resolution polygonal featuremodel generated from vector data as a feature into three-dimensionalscene source imagery in place of a lower resolution polygonalrepresentation of the feature, processes for systematically rendering atwo-dimensional representation of said scene containing saidhigh-resolution model, processes for capturing the two-dimensional pixelrepresentation of said rendered scene containing said high-resolutionmodel, processes for removing the inserted feature model inserted intothe scene source imagery; (b) data storage memory for storing saidtwo-dimensional pixel representation of said rendered scene containingsaid high-resolution model in a database for real time rendering of saidscene; and (c) a programmed computer processor with storage andincluding processes for rendering the two-dimensional representation ofthe scene on a display viewed at a first observer perspective andalternately rendering the three-dimensional representation of the sceneon the display when the scene is viewed from a second observerperspective closer than the first observer perspective.
 24. The computerprocessor of claim 23 wherein the programmed computer processor furthercomprises process for removing inserted polygons having a particularfeature code from said polygonal representation of scene to create areduced polygon representation; and process for storing said reducedpolygonal representation of said scene in a data base for rendering inreal time.
 25. The computer processor of claim 23 wherein the programmedcomputer processor further comprises process for removing coplanarpolygons from said polygonal representation of scene to create a reducedpolygon representation; and process for storing lower resolution datasets of said reduced polygonal representation of said scene in a database for rendering in real time.
 26. The computer processor of claim 23wherein the programmed computer processor further comprises a processfor systematically rendering an orthographic projection of the scenecontaining high resolution models.
 27. The computer processor of claim26 further comprising: process for removing inserted polygons from saidpolygonal representation of scene to create a reduced polygonrepresentation.
 28. The computer processor of claim 27 furthercomprising: process for storing said reduced polygonal representation ofsaid scene in a data base for rendering in real time.
 29. The computerprocessor of claim 26 further comprising: process for removing insertedpolygons having a particular feature code from said polygonalrepresentation of scene to create a reduced polygon representation. 30.The computer processor of claim 28 further comprising: process forstoring said reduced polygonal representation of said scene in a database for rendering in real time.